Avionics Full-Duplex Switched Ethernet (AFDX™) Ethernet switch networks utilize dedicated bandwidths while providing deterministic quality of service (QoS). The AFDX Ethernet switch standard is the Part 7 of the ARINC-664 “Aircraft Data Network” standard. It describes a deterministic switched Ethernet/IP network, that is, a switched network where a few constraints are applied. These constraints determine the allocated data transmission rate and the maximum packet or packet forwarding latency. AFDX networks are switched Ethernet local networks which employ data transmission in the form of IP packets encapsulated in Ethernet packets.
In a switched Ethernet network, each end device is connected to a switch via an individual physical link. In a network topology that contains more than one switch there will also be physical links between the different switches. A common setup for a switch is therefore to provide multiple ports that are used to establish physical links with other switches and with end devices. These physical links are operated in full duplex, i.e., each port at the switches as well as at the end devices can simultaneously send packets out onto the network and receive packets from the network. An egress port is the portion of a port that provides the functionality to send out packets onto the network, an ingress port is the portion of a port that provides the functionality to receive packets from the network.
The end devices may be producers, consumers, or both, producers and consumers of data packets. In an AFDX network, packets produced by one sourcing end device may be forwarded to exactly one destination end device only, but in typical scenarios packets produced by one sourcing end device will be forwarded to several destination end devices in parallel. Each destination end device will be delivered with a copy of the packet originally sent by the sourcing end device. These copies will be generated by the switches along the path through the network between the source end device and the destination end devices.
A virtual link is the set union of all physical links within the AFDX network that are used to transport the packets originating from the respective sourcing end device to all the assigned destination end devices. To unambiguously identify virtual links, each virtual link is assigned a virtual link identification number, abbreviated virtual link ID or VLID. Virtual links in the AFDX Ethernet network standard consist therefore of unidirectional multicast communication channels, whereby the VLID forms part of the multicast Ethernet MAC address and the multicast IP address used in the packet headers. In an AFDX network there are typically multiple virtual links present, whereby each end system may be the source of one or many virtual links and each virtual link may have a different set of receiving end systems.
A virtual link is implemented in an AFDX network by configuring the switches with respective forwarding rules. A forwarding table is the set of all rules that are configured on a certain switch. To configure one or several virtual links in an AFDX network subsequently requires the generation of a respective forwarding tables for each switch in the network.
AFDX Ethernet switches receiving a packet at an ingress port will read the VLID from the multicast destination MAC address found in the Ethernet packet header and will use this VLID to look-up in their forwarding table the set of egress ports to which the received packet shall be copied to and sent out from. The document US 2008/0043768 A1 for example discloses such a switch for an AFDX network.
In an AFDX network as intended by the ARINC-664 “Aircraft Data Network” standard each virtual link may only emanate from one sourcing end device in the whole network but may terminate at a number of receiving end devices. In testing environments incorporating AFDX networks, test system components are mixed with original equipment units under test. In order to keep a well-defined testing scenario, the test system components simulating real system components should use the same virtual link definitions including the same virtual link identifiers as the real system components. In testing environments, it should be possible to modify the payload of VLs, that is to receive VLs from one or several switches with test system components, to apply the modifications by use of the test system components, and to send the modified VLs again out onto the AFDX network using the same VLIDs. To save on testing environment costs, it should be possible to multiplex several distinct VLs having the same VLIDs onto the same physical links and being able to correctly de-multiplex them later on again. In large integration testing environments, it is desirable to be able to configure the testing environment's AFDX network such that the overall pool of resources can be used to conduct an all-encompassing large integration test as well as to simultaneously conduct multiple independent smaller-scaled tests without having to disconnect or rearrange the network's physical links, i.e., without having to change the physical wiring.
It is thus desirable to be able to forward two or more distinct VLs having the same VLID within an AFDX Ethernet switch utilizing the same ingress and egress ports and thus the same physical network links, and yet be able to distinguish between the different VLs within the switches. It is thus also desirable to be able to apply different forwarding rules in an AFDX Ethernet switch for the same VLIDs, dependent on the ingress ports through which the VLs are received.